KR20140045716A - Method for preparing organic-inorganic alloy films and the organic-inorganic films prepared therefrom - Google Patents

Abstract

The present invention relates to a method for preparing an organic-inorganic alloy film and the organic-inorganic film prepared thereby, and more particularly, to a method for preparing an organic-inorganic alloy film and the organic-inorganic film prepared thereby, wherein the method includes the steps of: 1) applying trimethylaluminium to a substrate by means of molecular layer deposition, purging the substrate with nitrogen gas, applying p-phenylenediamine to the substrate by means of molecular layer deposition, and forming an organic-inorganic hybrid thin film on the substrate; and 2) applying trimethylaluminium again to the substrate on which the hybrid thin film is formed by means of atomic layer deposition, purging the substrate with nitrogen gas, and forming an Al2O3 thin film on the substrate by applying water to the substrate by means of atomic layer deposition. According to the present invention, the method for preparing the organic-inorganic alloy film and the organic-inorganic film prepared thereby can provide excellent electrical characteristics such as high dielectric properties, leakage current density characteristics, dielectric breakdown characteristics, and dielectric constant characteristics, and the like, structural flexibility through the existence of the organic portion, and excellent stability through the existence of the inorganic portion, thus being adequately used as a charge trap layer. [Reference numerals] (AA) Upper cycle N for alloy film; (BB) Lower cycle X for composite layer by MLD; (CC) Lower cycle Y for Al_2O_3 layer by MLD; (DD,HH) TMA alternating; (EE,GG,II,KK) Purging; (FF) PPD alternating; (JJ) Water alternating

Description

Method for preparing organic-inorganic alloy film and organic-inorganic alloy film produced therefrom {Method for preparing organic-inorganic alloy films and the organic-inorganic films prepared therefrom}

The present invention relates to a method for producing an organic-inorganic alloy film using an atomic layer deposition method and a molecular layer deposition method, and an organic-inorganic alloy film produced therefrom.

Atomic layer deposition (ALD) is one of the vapor deposition methods for growing a variety of thin films, including oxide, nitride and metal thin films, through self-limiting chemisorption. ALD alternately exposes the appropriate precursor vapor and reactant gas to a substrate that is kept sufficiently low to avoid pyrolysis of the precursor and purges the inert gas into the reaction chamber for a time between exposure of the precursor vapor and the reactant gas. . Thus, each cycle of the ALD process generally consists of precursor exposure-purging-reaction gas exposure-purging. Film growth occurs through chemisorption between gas molecules (ie, precursor vapors or reaction gases) and reactive functional groups (eg, hydroxyl groups or chemisorbed organometallic groups) on the surface. Once the empty adsorption site is saturated with adsorption molecules to form a single monolayer, the precursor or reaction gas does not chemically adsorb to the monolayer in excess. As a result, film growth by ALD is self-limiting.

Because of this self-limiting mechanism, ALD generally enables excellent thickness control, uniform growth over large areas, and the formation of conformal films over three-dimensional structures. Similar self-limiting surface reactions can also be applied to organic polymer thin films, such as polyamides and polyimides, using bifunctional organic monomers (George, SM; Yoon, B .; Dameron, AA). Acc . Chem . Res . 2009 , 42 , 498 .; Yoshimura, T .; Tatsuura, S .; Sotoyama, W. Appl . Phys . Lett . 1991 , 59 , 482 .; Bitzer, T .; Richardson, NV Appl . Phys . Lett . 1997 , 71 , 662 .; Kim, A; Filler, MA; Km, S .; Bent, SF J. Am . Chem . Soc . 2005 , 127 , 6123 .; Du, Y .; George, SM J. Phys . Chem . C 2007 , 111 , 8509 .; Putkonen, M .; Harjuoja, J .; Sajavaara, T .; Niinisto, L. J. Mater . Chem . 2007 , 17 , 664 .; Adamczyk, NM; Dameron, AA; George, SM Langmuir 2008 , 24 , 2081). This modification of ALD to organic polymer films is called molecular layer deposition (MLD) because molecular fragments of organic precursors are deposited during each ALD cycle.

The functionality of MLDs for organic layers and the functionality of ALDs for inorganic films offers potential for organic-inorganic hybrids or alloy films. In the past, several researchers have described a series of reactions between metal precursors (eg trimethylaluminum (TMA), diethylzinc, titanium tetrachloride and zirconium tetra- t -butoxide) and diols (eg ethylene glycol). Have reported hybrid polymer films called metalcones (e.g., alucon, gincon, titanic and zircon) (Dameron, AA; Seghete, D .; Burton, BB; Davidson, SD; Cavanagh, AS; Bertrand, JA; George, SM Chem . Mater . 2008 , 20 , 3315 .; Peng, Q .; Gong, B .; VanGundy RM; Parsons, GN Chem . Mater . 2009 , 21 , 820 .; Yoon , B .; O'Patchen, JL; Seghete , D .; Cavanagh, AS; George, S. M. Chem Vap Deposition 2009, 15, 112 .; George, SM;.. Lee, BH; Yoon, B .; Abdulagatov, AI; Hall, RA J. Nanosci Nanotechnol 2011 11, 7948 .; Hall, RA;... Abdulagatov, AI; George, SM In AVS 58 th Annual International Symposium and Exhibition ; Nashville, Tennessee, October 30-November 4, 2011; AVS, Chico CA, 2011). In addition to metal cones by MLD, various organic-inorganic hybrid materials have been studied as materials for thin film formation because of the possibility of combining the unique properties of organic and inorganic parts (George, SM; Lee, BH; Yoon). , B .; Abdulagatov, AI; Hall , RA J. Nanosci Nanotechnol 2011 11, 7948 .; Hall, RA;... Abdulagatov, AI; George, SM In AVS 58 th Annual International Symposium and Exhibition ; Nashville, Tennessee, October 30-November 4, 2011; AVS, Chico CA, 2011).

The organic-inorganic composite film can function as a scaffold when it is desired to obtain a porous oxide film of inorganic elements by calcination (Liang, X .; Yu, M .; Li, J .; Jiang, YB;... Weimer , A. W Chem Commun 2009, 7140). Functional materials such as transparent conductive films and organic magnetic films have been recently studied using MLD (Yoon, B .; Lee, Y .; Derk, A .; Musgrave, CB; George, SM ECS Trans. 2011 , 33 , 191 .; Kao, CY; Yoo, JW;.. Min, Y .; Epstein, AJ ACS Appl Mater Interfaces 2012, 4, 137), a wide range of new applications for MLD, for example, treating cancer and lithographic patterned areas It has been proposed in (Yoshimura, T .; Yoshino, C .; Sasaki, K .; Sato, T .; Seki, M. IEEE J. Sel. Topics Quantum Electron. 2011 , 18 , 1192 .; Zhou, H .; Bent, SF ACS Appl . Mater . Interfaces 2011 , 3 , 505). However, their application is limited because organic-inorganic composite films are somewhat air sensitive due to the presence of unstable organic moieties in the film. Accordingly, crosslinking of organic moieties or alloying of MLD composite layers with ALD inorganic layers have been attempted to improve the stability of MLD films (George, SM; Lee, BH; Yoon, B .; Abdulagatov, AI; Hall, RA J. Nanosci Nanotechnol 2011 11, 7948 .; Hall, RA;... Abdulagatov, AI; George, SM In AVS 58 th Annual International Symposium and Exhibition ; Nashville, Tennessee, October 30-November 4, 2011; AVS, Chico CA, 2011 .; Lee, BH; Im, KK; Lee, KH; Im, S .; Sung, MM Thin Solid Films 2009 , 517 , 4056 .; Loscutoff, PW; Zhou, H .; Clendenning, SB; Bent, SF ACS Nano 2010 , 4 , 331 .; Lee, BH; Yoon, B .; Anderson, VR; George, SM J. Phys . Chem . C 2012 , 116 , 3250).

George et al. Recently reported that alloy films that can adjust density can be obtained by mixing an alucon MLD layer and an Al ₂ O ₃ ALD layer (Yoon, B .; Anderson, VR; George, SM J. Phys . Chem . C 2012 , 116 , 3250). Since alucon MLD films are typically less dense than Al ₂ O ₃ ALD films, the density of the alloy films can be varied by controlling the relative number of ALD and MLD cycles in the reaction sequence. This is a typical way to trade off dielectric constant and leakage current in high k thin films.

In recent years, organic thin film transistors (OTFTs) have gained great attention as promising components of flexible electronics, and therefore, organic-inorganic composite or alloy films by MLD can be employed as gate-dielectric or semiconductor films in OFTF. Facts have also been demonstrated (Lee, BH; Ryu, MK; Choi, SY; Lee, KH; Im, S .; Sung, MM J. Am . Chem . Soc . 2007 , 129 , 16034 .; Yoon, B. Seghete, D .; Cavanagh, AS; George, SM Chem . Mater . 2009 , 21 , 5365 .; Lee, BH; Im, KK; Lee, KH; Im, S .; Sung, MM Thin Solid Films 2009 , 517 , 4056 .; Lee, BH; Lee, KH; Im, S .; Sung, MM J. Nanosci . Nanotechnol . 2009 , 9 , 6962 .; Park, Y .; Han, KS; Lee, BH; Cho, S .; Lee, KH; Im, S .; Sung, MM Org. Electron . 2011 , 12 , 348).

The present invention has excellent electrical properties such as excellent dielectric properties, leakage current density characteristics, dielectric breakdown characteristics and dielectric constant characteristics, structural flexibility due to the presence of organic parts, and excellent stability due to the presence of inorganic parts. An object of the present invention is to provide an organic-inorganic alloy film suitable for use as a charge trapping layer of an electric device, and an organic-inorganic alloy film prepared therefrom.

In order to solve the first problem,

1) treating trimethylaluminum on the substrate by molecular layer deposition, purging with nitrogen gas, and then treating p-phenylenediamine by molecular layer deposition to form an organic-inorganic hybrid thin film on the substrate; And

2) Treating trimethylaluminum by atomic layer deposition on the substrate on which the organic-inorganic hybrid thin film is formed, purging with nitrogen gas, and treating water by atomic layer deposition, the Al ₂ O ₃ thin film on the substrate Forming steps

It provides a method for producing an organic-inorganic alloy film comprising a.

According to one embodiment of the present invention, the thickness of the organic-inorganic hybrid thin film is 0.1 to 1 nm, the thickness of the Al ₂ O ₃ thin film may be 0.1 to 1 nm.

According to another embodiment of the present invention, after step 1) is repeated once to 5 times, step 2) may be performed once to 10 times.

According to another embodiment of the present invention, the relative ratio between the number of repetitions of step 1) and the number of repetitions of step 2) may be 1: 1 to 1:10.

According to another embodiment of the present invention, the entire step including the steps 1) and 2) may be repeated once to 100 times.

According to another embodiment of the present invention, in the molecular layer deposition method of step 1), the dose of trimethylaluminum is 1 × 10 ^-5 mol / s to 1 × 10 ^-3 mol / s, the p- The dosage of phenylenediamine may be 1 × 10 ⁻⁷ mol / s to 1 × 10 ⁻⁵ mol / s.

According to another embodiment of the present invention, in the atomic layer deposition method of step 2), the dose of trimethylaluminum is 1 × 10 ^-5 mol / s to 1 × 10 ^-3 mol / s, and the administration of water The amount may be 1 × 10 ⁻⁵ mol / s to 1 × 10 ⁻³ mol / s.

According to another embodiment of the present invention, the purge process by nitrogen gas of steps 1) and 2) may be performed for 0.1 seconds to 10 minutes.

According to another embodiment of the present invention, step 1) may be performed in a molecular layer deposition apparatus maintained at a temperature of 100 ° C to 400 ° C and a pressure condition of 100 mTorr to 10 Torr.

According to another embodiment of the present invention, step 2) may be performed in an atomic layer deposition apparatus maintained at a temperature of 100 ° C to 400 ° C and a pressure condition of 100 mTorr to 10 Torr.

According to another embodiment of the present invention, the substrate may be a substrate made of Si, glass, plastic or metal.

In order to solve the second problem,

It provides the organic-inorganic alloy film produced by the above method.

According to the present invention, it has excellent electrical properties such as excellent dielectric properties, leakage current density characteristics, dielectric breakdown characteristics and dielectric constant characteristics, etc., has structural flexibility due to the presence of organic parts, and excellent stability due to the presence of inorganic parts. Therefore, it is possible to provide a method for preparing an organic-inorganic alloy film suitable for use as a charge trapping layer of various electric devices, and an organic-inorganic alloy film prepared therefrom.

1 is a view showing a schematic process cycle for the manufacturing method of the organic-inorganic alloy film according to the present invention.
Figure 2 is a schematic diagram of the surface reaction of the organic-inorganic hybrid thin film is formed by the MLD process in the manufacturing method of the organic-inorganic alloy film according to the present invention.
3 is a graph showing the change in thickness of the organic-inorganic hybrid film with the exposure time of the PPD.
4 is a graph showing the thickness increase rate according to the exposure time in air of the composite film ( X = N = 50 and Y = 0) grown at 400 ℃.
FIG. 5 is a graph showing X-ray photoelectron spectra of a composite film ( X = N = 50 and Y = 0) and a 1: 4 alloy thin film grown at 400 ° C.
6 is a graph showing the thickness (filled circle) and non-uniformity rate (empty circle) of the X: Y alloy film grown at 400 ° C.
FIG. 7 is a graph showing the thickness according to the PPD exposure time of the 1: 4 alloy film (N = 20) grown at 400 ° C.
8 is a graph showing the thickness of a 1: 4 alloy film versus the number of top cycles at various growth temperatures.
9 is a 1: 4 alloy film (square), composite film (triangle) and Al ₂ O ₃ It is a graph showing the growth rate according to the growth temperature of the film (circular).
FIG. 10 is a graph showing (a) current density-field curves and (b) capacitance-voltage curves measured from Au / 1: 4 alloy (46 nm) / SiO ₂ (2 nm) / p-Si capacitors. to be.
FIG. 11A is an HR-TEM image of a cross section of a flash memory capacitor structure fabricated in accordance with the present invention, and FIG. 11B is a normalized capacitance at a sweep range of -10 to 10 V (dotted line) and -25 to 25 V (solid line). It is a graph showing the applied voltage curve (insertion graph shows the width of the hysteresis versus the sweep range).
12 is a graph showing the write (filled circle) and erase (empty circle) characteristics of a memory capacitor having a 1: 4 alloy film as CTL.
FIG. 13 is a graph showing retention characteristics of electrons trapped in a memory capacitor by applying 20V for 10 seconds.

Hereinafter, the present invention will be described in more detail with reference to the drawings.

In the present invention, 1) trimethylaluminum is treated on a substrate by molecular layer deposition, purged with nitrogen gas, and then p-phenylenediamine is formed on the substrate by molecular layer deposition to form an organic-inorganic hybrid thin film on the substrate. Making; And 2) Al ₂ O ₃ thin film on the substrate by treating trimethylaluminum by atomic layer deposition, purging with nitrogen gas, and then treating water by atomic layer deposition on the substrate on which the organic-inorganic hybrid thin film is formed. It provides a method for producing an organic-inorganic alloy film comprising the step of forming a.

Therefore, in the method for producing an organic-inorganic alloy film according to the present invention, an organic-inorganic hybrid thin film is first formed by molecular layer deposition (MLD), and then an Al ₂ O ₃ thin film is formed by atomic layer deposition. The reason why the organic-inorganic alloy film according to the present invention has a double layer structure is that the organic-inorganic hybrid thin film can be grown by the self-limiting growth mechanism of the MLD, but the thin film formed is extremely in the air. Because it is sensitive and unstable, there is a need to stabilize it. Therefore, in the present invention, this problem was solved by alloying the organic-inorganic hybrid thin film formed by MLD with the Al ₂ O ₃ thin film.

1 shows a schematic process cycle for the process according to the invention for producing organic-inorganic alloy films from TMA, PPD and water. Referring to FIG. 1, the manufacturing method according to the present invention includes a sub cycle X for producing an organic-inorganic hybrid thin film by MLD and a sub cycle Y for alloying an Al ₂ O ₃ thin film by ALD. Higher cycle N for producing the alloy film.

In the present invention, the thickness of the organic-inorganic hybrid thin film formed by MLD can be adjusted by adjusting the number of times the sub-cycle X, specifically can be adjusted to a thickness of 0.1 to 1nm, likewise Al ₂ The thickness of the O ₃ thin film may be adjusted by adjusting the number of times of the sub cycle Y, and specifically, may be adjusted to a thickness of 0.1 to 1 nm. If the thickness of the organic-inorganic hybrid thin film is less than 0.1nm, there is a problem that the charge storage capacity is significantly lowered, and if it exceeds 1nm, there is a problem that the nano-laminate thin film is generated rather than the alloy thin film is not preferable, Al ₂ O _When the thickness of the ₃ thin film is less than 0.1 nm, there is a problem that the stability improvement effect of the hybrid thin film is weak, and when it exceeds 1 nm, as described above, there is a problem in that the nanolaminate thin film is generated, which is not preferable. Therefore, in consideration of the thickness range, step 1) may be repeated once to five times, and step 2) may be repeated once to ten times.

In particular, by adjusting the relative ratio between the number of repetitions (X) of step 1) and the number of repetitions (Y) of step 2), it is possible to adjust the relative thickness ratio of the Al ₂ O ₃ thin film to the organic-inorganic hybrid thin film, When the ratio is in the range of 1: 1 to 1:10, there is an effect that excellent electrical properties and structural stability can be simultaneously achieved.

The overall thickness of the alloy film according to the present invention can be adjusted by adjusting the value of N in Figure 1, specifically, to repeat the entire step including the steps 1) and 2) 1 to 100 times. However, additional iterations are possible if the target thickness is thicker.

2, in the manufacturing method according to the present invention, a schematic diagram of the surface reaction of the MLD process of the organic-inorganic hybrid thin film is shown. The organic-inorganic hybrid thin film is formed by treating trimethylaluminum by MLD on the substrate as described above, purging with nitrogen gas, and then treating p-phenylenediamine (PPD) with MLD. Upon completion of the first reaction by trimethylaluminum treatment, aluminum is attached to an amino group on the substrate surface and methane is released as a byproduct. Subsequently, when the second reaction by PPD treatment is completed after the nitrogen purging process, phenylenediamine is attached to aluminum and methane is released as a by-product. At this time, since the amine group of phenylenediamine is exposed, the next cycle through the same process can be repeated.

In the treatment of trimethylaluminum and p-phenylenediamine by the MLD, the dosage of trimethylaluminum may be 1 × 10 ⁻⁵ mol / s to 1 × 10 ⁻³ mol / s, and the p-phenylene The dosage of diamine may be 1 × 10 ⁻⁷ mol / s to 1 × 10 ⁻⁵ mol / s. If the dose of TMA is less than the above range, there is a problem that the TMA supply time is too long, and if it exceeds the above range, there is a problem of excessive consumption of the precursor, even if the dose of phenylenediamine is less than the above range There is a problem that the supply time of the diamine is too long, and even if it exceeds the above range, there is also a problem of waste of phenylenediamine due to excessive supply, which is not preferable.

In addition, in steps 1) and 2) of the present invention, that is, MLD and ALD, the purge process by nitrogen gas may be performed for 0.1 second to 10 minutes, and self-limiting growth behavior when the purge process is too short. There is a problem that does not appear, and if it is too long, there is a problem that wastes the purge gas is not preferable.

On the other hand, the process conditions of the molecular layer deposition apparatus and atomic layer deposition apparatus used in the manufacturing method according to the present invention can be maintained both at a temperature of 100 ℃ to 400 ℃ and pressure conditions of 100mTorr to 10Torr.

The invention is applicable to a variety of substrates for electronic devices, but is not limited to, for example, a variety of substrates of a material such as Si, glass, plastic or metal.

In addition, the present invention provides an organic-inorganic alloy film prepared by the above method, the alloy film according to the invention can be seen from the following examples, excellent dielectric properties, leakage current density characteristics, dielectric breakdown characteristics and Since it has excellent electrical properties such as dielectric constant properties and excellent stability, it is suitable for use as a charge trapping layer in various electric devices.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the following examples are intended to assist the understanding of the present invention and should not be construed as limiting the scope of the present invention.

Materials and equipment

Using a laminar flow type ALD reactor (ATOMIC-CLASSIC 2nd edition, CN-1 Co., Ltd.) on boron doped p -type (100) Si wafers with resistivity of 5 to 20 Ω-cm All thin films were grown. Although the reactor used in this example can handle 6 inch wafers, 6 square wafers are mounted by placing five square specimens (2 × 2 cm ² ) in the center, left, right, top and bottom positions of the 6 inch substrate fixture. The nonuniformity was evaluated. The specimen was used without removing the natural oxide film. TMA (UP Chemical Co., Ltd) and water were vaporized from an external metal canister at room temperature and led to a reactor through a solenoid valve without a carrier gas. The doses of TMA and water were ˜1.0 × 10 ⁻⁴ and ˜7.2 × 10 ⁻⁵ mol / s, respectively. PPD (Sigma-Aldrich) at high purity (99.999%) N ₂ at 145 ° C (100 standard cubic centimeters per minute, sccm) and delivered to the reactor at a dosage of ˜2.8 × 10 ⁻⁶ mol / s. High purity N ₂ gas was used at a flow rate of 400 sccm to purge the reactor. All conveying lines were kept at 120 ° C. Specimen temperatures adjusted with thermocouple inserted 6 inch wafers were determined in a temperature range of 200-400 ° C. The base pressure of the reactor was less than 10 mTorr, and ALD was run in the operating pressure range of 200 to 600 mTorr.

The organic-inorganic hybrid thin film formed by molecular layer deposition was grown by alternately exposing TMA (1 second) and PPD (7 seconds except FIGS. 3 and 7), and purging the TMA and PPD in this molecular layer deposition sequence. The time was 30 and 60 seconds respectively. Al ₂ O ₃ thin films formed by atomic layer deposition were deposited from TMA and water as Al precursors and reactive gases, respectively. After alternating TMA and water for 1 second, the reactor was purged for 10 seconds.

The grown films were measured with a spectroscopic ellipsometer (SE, MG-1000, NanoView). The angle of incidence of the polarized light at SE was fixed at around 70 °, and the incident light had a spectral range of 1.5 to 5.0 eV. In order to determine the initial value of the thickness for fitting the measured data, the measured data were first fitted with the Al ₂ O ₃ reference values of the real part and the imaginary part of the dielectric complex function provided by NanoView (Thomas, ME; Tropf, WJ). In Handbook of Optical Constants of solids ; Palik, ED, Ed .; Academic Press: San Diego, CA, 1998; p. 653). The measured data was then fitted to the Cauchy dispersion function for all films (Jellison, Jr. GE; Modine, FA Appl . Phys . Lett. 1996 , 69 , 371).

By using the five thicknesses obtained at the center, top, bottom, left and right positions in a 6 inch substrate fixture, the standard deviation of the thickness was divided by the average value to evaluate the non-uniformity of the MLD process. The stability of the film was estimated by measuring the change in thickness of the film exposed to the atmosphere at room temperature.

X-ray photoelectron spectroscopy (XPS) spectra were collected with an AXIS-NOVA (Kratos Inc.) spectrometer using Al Kα emission light (1486.6 eV). Binding energy was measured using the C 1s peak (285.0 eV) of adventitious carbon as internal standard. High resolution transmission electron microscopy (HR-TEM) images were obtained for the cross-sections of memory capacitors fabricated using focal ion beams of gallium ions.

Au / alloy film / Natural SiO ₂ (2 nm) / p- Si (100) structure was deposited by thermal evaporation through a metal shadow mask for the upper electrode to investigate the electrical properties of the alloy film. The capacitor of was prepared. The area of the Au electrode was ˜1.26 × 10 ⁻³ cm ² . Flash memory capacitors with 1: 4 alloy film as CTL were also made. The structure of these memory capacitors is Au (50nm) / Al ₂ O ₃ (20.5 nm) / composite film (1.4 nm) / Al ₂ O ₃ (6.5 nm) / SiO ₂ (2 nm) / p- Si, in which the thick Al ₂ O ₃ film and the thin Al ₂ O ₃ film They act as blocking oxides and tunnel oxides, respectively. Tunnel Al ₂ O ₃ (ALD 70 cycles), CTL (1: 4 complex, N = 3) and blocking Al ₂ O ₃ (ALD 220 cycles) at 400 ° C Successive depositions were made on the p- Si substrate with native SiO ₂ without breaking the vacuum of the reactor. The current density-voltage (JV) and capacitance-voltage ( C - V ) characteristics of the capacitor were measured with a semiconductor parameter analyzer (HP 4145B) and an LCR meter (HP 4284A), respectively.

Results and Discussion

1.organic-inorganic hybrid film made from TMA and PPD (step 1))

Figure 2 shows a schematic of the surface response to MLD ( X = N and Y = 0) of the organic-inorganic hybrid film according to the present invention. In the first half reaction of the MLD, the amino group on the surface (or hydroxyl group in the first cycle) is exposed to the TMA and methane is released as a byproduct. The resulting surface is exposed to PPD in the second half reaction and methane is released again as a byproduct. Eventually, the amino groups on the surface are restored in the next cycle.

Figure 3 shows the change in thickness of the organic-inorganic hybrid film with the exposure time of the PPD. The hybrid film was deposited at 400 ° C. by MLD ( X = N = 50 and Y = 0). As the exposure time of the PPD increased, the thickness initially increased and then saturated over 5 seconds. Self-limiting growth of the hybrid film was observed in the MLD, but the thickness was not uniform at the 6 inch wafer size, and the thickness uniformity was reproduced in the run-to-run study mainly due to the low stability of the film in air. Can not.

In general, the metalcone exhibits a decrease in thickness when exposed to air after MLD, but the organic-inorganic hybrid film according to the present invention has a large increase in thickness, for example, after 2 weeks, the thickness is ~ 30 as shown in FIG. Increased by%. In this regard, Sood et al. Are Ti-4,4′-oxydianilines that are stable in the atmosphere when grown in the range of 250-490 ° C., while exhibiting instability in air when grown at lower temperatures (160-230 ° C.). MLD of composite films has been reported (Sood, A .; Sundberg, P .; Malm, J .; Karppinen, M. Appl . Surf . Sci . 2011 , 257 , 6435).

Although the chemical mechanism of the thickness increase is not clear, it is assumed in the present invention that the thickness increase phenomenon is caused by an unwanted chemical reaction between the hybrid film and moisture (and / or oxygen). This unwanted reaction occurs from the surface of the hybrid film and chemically altered layers can be produced. This phenomenon is similar to the growth of silicon oxide from Si substrates when exposed to O ₂ or H ₂ O.

Also related, Deal and Grove's model describes the kinetics of silicon oxidation (Deal, BE; Grove, AS J. Appl . Phys . 1965 , 36 , 3770), according to these models, the initial stage of oxide growth from Si. In the step, the thickness of the oxide is linearly proportional to the oxidation time because of reaction-controlled oxidation. However, the oxide thickness is proportional to the square root of the oxidation time, since there is an oxide layer between O ₂ (or H ₂ O) and Si during the long oxidation time so that the oxidation is diffusion-controlled. Similarly, in the present invention, the increase in thickness of the organic-inorganic hybrid film is initially proportional to the exposure time in air, and then the chemical change of the hybrid film is somewhat diffused because there is a chemically changed layer between the air and the unchanged hybrid layer. It is assumed that it is controlled and thus represents a parabolic form of dynamics.

5 shows the XPS spectrum (top view) of the hybrid film ( X = N = 50 and Y = 0) according to the invention grown at 400 ° C. exposed to air for several months. The other peaks were corrected by setting the lowest binding energy C 1s peak presumably derived from the amorphous CH species to 285.0 eV. The distinct peaks of carbon located at higher binding energies (~ 288.9 eV) are generally associated with large electron attracting C═O groups. According to the reaction scheme proposed in FIG. 2, this hybrid film should be free of C═O species. This may also be derived from amorphous carbon, but the present invention assumes that these peaks result from chemical changes in the hybrid film by H ₂ O and / or O ₂ when exposed to air. Indeed, the O 1s peak, which should not be present in such hybrid films, is also observed at ˜531.6 eV.

Al 2p peaks appear at ˜74.5 eV as predicted in FIG. 2, and N 1s peaks are observed at ˜399.5 eV slightly smaller than the reported value of PPD (˜399.8 eV). The binding energy ranges of N ⁺ , N ^{2 +} and N ^{3 +} oxidation states in aluminum oxynitride have been recently reported to be 399.3 to 399.9 eV, 402.0 to 402.3 eV and 404.1 to 404.5 eV, respectively (Wang, PW; Hsu). , JC; Lin, YH; Chen , HL Appl Surf Sci 2010, 256, 4211 .; Wang, PW;... Hsu, JC; Lin, Y. H;.. Chen, HL Surf Interface Anal 2011, 43, 1089 ). The position of N 1s in FIG. 5 is similar to the N + oxidation state, presumably due to chemical changes occurring in the hybrid film in air.

2.organic and inorganic alloy film (2 step))

The hybrid layer was alloyed with the Al ₂ O ₃ layer because of the low stability of the organic-inorganic hybrid film in air. 6 shows the growth rate (growth thickness per upper cycle) of the X : Y alloy film grown at 400 ° C. The number of subcycles for the composite layer was fixed at X = 1. As the lower cycle ( Y ) for the Al ₂ O ₃ layer increases by 1, the growth rate becomes linearly faster. The increase in growth rate (0.092 nm / up cycle) when Y increases by 1 agrees well with the typical growth rate of Al ₂ O ₃ films at 400 ° C. with TMA and water. Furthermore, the unstable composite layer is Al ₂ O ₃ The nonuniformity of the alloy film at 6 inch wafer-size also greatly improves as Y increases because it can be protected from air exposure by the layer. Indeed, the 1: 4 alloy film showed a much smaller thickness increase of less than 5% after tens of weeks, while the thickness of the organic-inorganic hybrid film increased by 30% in two weeks under air exposure.

Referring to FIG. 7, a 1: 4 alloy film grown at 400 ° C. exhibits a clear self-limiting growth behavior when exposed for longer than 7 seconds. In comparison with FIG. 3, the thickness of the alloy film is gradually saturated, which is presumably Al ₂ O ₃ rather than the composite layer. This is probably due to the higher density of adsorption sites in the bed.

The alloy film was grown for 10, 20, 30 and 40 upper cycles, respectively, in the temperature range of 200-400 ° C. to investigate the linear growth of the 1: 4 alloy film over the number of upper cycles. Among them, thickness data at 200, 300 and 400 ° C. are shown in FIG. 8 (data at 250 and 350 ° C. are not shown for clarity). As typically expected in ALD and MLD, the thickness of the alloy film increases linearly with the number of higher cycles. The growth rate of the alloy film measured from the slope of FIG. 8 at each growth temperature is shown in a square in the graph of FIG. The growth rate of a 1: 4 alloy film decreases with increasing temperature (0.69 nm / up cycle from 0.69 nm / up cycle at 200 ° C. to 0.46 nm / up cycle at ~ 400 ° C.), but typical flats at growth temperature by self-limiting chemisorption are 350 Observed at 400 ° C.

Because of the poor stability of the composite film, it is practically difficult to determine the growth rate of the composite film. Therefore, in the present invention, ALD of the Al ₂ O ₃ film was performed in the same temperature range as that of the alloy film as shown in FIG. 9. The growth rate of the composite layer in the alloy film using the growth rate of the Al ₂ O ₃ film at each growth temperature can be indirectly evaluated as shown by the triangle of FIG. As a result, the growth rate of the composite layer is in the range of 0.09 to 0.17 nm / subcycle. Furthermore, the heterogeneity (6 inch wafer-size) of the composite layer (~ 2.0%) and the 1: 4 alloy film (~ 3.1%) at 400 ° C. was comparable to the Al ₂ O ₃ film (~ 1.1%) at the same temperature. Excellent enough to be. Thus 400 ° C. was determined as the growth temperature for device manufacture.

5 also shows XPS spectra for a 1: 4 alloy film (bottom figure) grown at 400 ° C. Since the composite layer ( X = 1) was alloyed and atomically mixed with the Al ₂ O ₃ layer ( Y = 4), the intensity of the C 1s and N 1s peaks was significantly reduced compared to those of the composite film. Also, because the nitrogen atoms show very low sensitivity in XPS, the N 1s peaks in the 1: 4 alloy film are much weaker. In contrast, the Al 2p and O 1s peaks are much stronger due to the presence of the Al ₂ O ₃ layer.

3. Electrical Characteristics of Alloy Film

The electrical properties of the 1: 4 alloy film grown at 400 ° C. for 100 upper cycles were characterized for the capacitor structure (Au / alloy (46 nm) / SiO ₂ (2 nm) / p- Si). The capacitor area was 1.26 × 10 ⁻³ cm ^2, defined using a shadow mask during Au deposition. 10A shows the current density-electric field ( J - E ) curve of the 1: 4 alloy film. The leakage current density is ˜2.3 × 10 ⁻⁸ A / cm ² at an electric field of 1 MV / cm, which is the reported value (10 ⁻⁸ to 10 ⁻⁹ A / cm ² ) of Al ₂ O ₃ film grown from TMA. Slightly higher than However, the dielectric breakdown of the alloy film appeared at ˜2.9 MV / cm, much lower than that of the Al ₂ O ₃ film (6-8 MV / cm), probably due to the presence of organic parts in the alloy film.

10b shows a capacitance-voltage ( C - V ) curve of Au / alloy / SiO ₂ / p- Si at 100 kHz. This represents the typical characteristics of an n -type metal-oxide-semiconductor ( n- MOS) capacitor having an accumulation region at a negative applied voltage and an inversion region at a positive voltage. The change in capacitance with applied voltage is caused by the change in the thickness of the carrier depletion region (ie, the space charge region) of the p -Si substrate. At large negative voltages where the silicon surface is in an accumulated state, the measured capacitance is equivalent to the series capacitance of the approximately 1: 4 alloy and the native SiO ₂ layer. Considering a 2 nm thick natural oxide film with a dielectric constant of 3.9, the estimated dielectric constant of a 4: 1 alloy film is ˜6.2 from the following series capacitance equation:

1 / C _D = 1 / C _SO + 1 / C _A (1)

Where C _D is the dielectric capacitance measured in the accumulation region (-4V), and C _SO and C _A are the capacitances of SiO ₂ and the alloy, respectively. The value of the dielectric constant is much lower than the dielectric constant (7-8) of the ALD Al ₂ O ₃ film because the 4: 1 alloy film contains the organic moiety.

Considering the resistivity of p- Si (5-20 Ω-cm) used, the doping concentration of p- Si is ˜1 × 10 ¹⁵ / cm ³ . The work function φ _M of Au is 5.31 to 5.47 eV, depending on its crystal plane, and the electron affinity ( x ) of Si is 4.05 eV. The work function difference ( φ _MS ) between Au and p -Si is determined by the following equation:

φ _MS = φ _M- ( x + ( E _C - E _F ) / q ) (2)

Where q , E _C and E _F are the magnitude of the electron charge, the conduction band edge and the Fermi energy, respectively. Using the doping concentration and intrinsic carrier concentration (˜1 × 10 ¹⁰ / cm ³ ) of Si at room temperature, the value of E _C - E _F is -0.86 eV, thus φ _MS is estimated to be approximately 0.40-0.56 eV.

If there is no charge at the interface with the alloy film and the natural oxide film immediately after growth, the flat band voltage V _FB is equal to φ _MS / q between Au and Si.

V _FB (No charge) =φ _MS/q (3)

However, as shown in FIG. 10B, V _FB was determined to be approximately 1.8 V from a flat band capacitance ( C _FB ) of ˜0.06 nF calculated from the following equation:

C _FB = 1 / (1 / C _D + L _D / Ae _s ) at V _FB (4)

Where A is the area of the capacitor (1.26 × 10 ⁻³ cm ² ), L _D is the Debye length (0.13 mm at the doping concentration of 1 × 10 ¹⁵ cm), and e _s is the dielectric constant of the silicon (11.9 × 8.854 × 10 ^-14 F / cm). The V _FB (1.8 V) and _{φ MS / q (0.40 ~ 0.56} V) when the value, in the present invention, mobile two-way flat band voltage _{(Δ V FB = 1.24 ~ 1.40} V) compared to those of the observed. In general, V _FB is shifted from φ _MS / q in the presence of charge density ( Q ) by the following equation:

V _FB = φ _MS / q - QA / C _D (5)

Subtracting equation 3 from equation 5 is

Δ V _FB = -QA / C _D (6)

Accordingly, the bi-directional movement values (Δ V _FB> 0) is due to the negative charge on the capacitor dielectric. The number density ( N ) of the charge can be simply calculated by N = Q / q and N can be expressed as follows by substituting Q = qN into equation 6:

N = ΔV _FB C _D/qA (7)

Therefore, the number density of negative charges in the capacitor is in the range of 8.7 × 10 ¹¹ to 9.8 × 10 ¹¹ / cm ² .

Among the various charges, such as fixed charges, oxide-captured charges and interfacial-captured charges, the parallel shift of the CV curve is generally due to the fixed charges. Since the fixed charge in the SiO ₂ / Si structure is usually sufficiently negligibly low (number 10 ¹⁰ / cm ² ) relative to the estimate, the fixed negative charge is presumably due to the interface with the alloy film and / or SiO ₂ .

As indicated by the arrows in FIG. 10B, note the CV curve when the applied voltage is swept backwards from inversion to scale (4 V to -4 V) and then again forward to inversion (-4 V to 4 V). All that matters is a clockwise hysteresis. In general, hysteresis is due to trapped charge in the volume of the dielectric. Recently, Jeong et al. Reported that organic-inorganic composite films (aminopropyl-silsesquioxanes) show distinct clockwise hysteresis and that nitrogen-related molecular defects act as electron trapping centers (Lee, DH; Jeong). , HD J. Phys . Chem . C 2008 , 112 , 16984). Yoshida et al. Also reported the charge trapping effect of MLD polyimide films (Yoshida, S .; Ono, T .; Esashi, M. Nanotechnology 2011 , 22 , 335302). Hysteresis is believed to originate from the center of charge traps in the alloy film where electrons or holes can be captured depending on the polarity of the applied voltage. When a positive voltage is applied in the reverse sweep, holes may be injected from the upper electrode into the trap of the alloy, and the positively charged trap site moves in the negative flat band (i.e., in the negative curve of the CV curve) according to equation (6). Appears. Similarly, negatively charged trap sites formed by electron injection of the forward sweep appear as bidirectional flat band shifts (ie bidirectional shifts of the CV curve). It should be noted that charge injection from the substrate may not be preferred over charge injection from the upper electrode because there is a natural SiO ₂ between the alloy film and Si.

4. Charge trapping behavior of alloy film

In order to confirm the charge trapping capability of the alloy film, the present invention fabricated a flash memory capacitor structure including an upper electrode, a blocking oxide, a charge trapping layer (CTL), a tunnel oxide, and a p- Si substrate. The HR-TEM image shown in FIG. 11A shows a cross-sectional view of the memory stack. Although natural SiO ₂ and Si substrates are clearly seen, tunnel Al ₂ O ₃ , CTL (1: 4 alloy) and blocking Al ₂ O ₃ are difficult to distinguish. In particular, it should be noted that the three layers in the memory stack are internally based on Al ₂ O ₃ . In addition, this figure supports that the 1: 4 alloy was prepared by atomically mixing the composite layer and the Al ₂ O ₃ layer.

By applying a positive voltage pulse to the upper electrode in the operation of the charge trap flash memory, electrons are trapped from Si through the tunnel oxide (or holes are released from the CTL), which is called 'programming'. Erasing is accomplished by applying a negative voltage pulse to the upper electrode. At the erase voltage electrons exit from the trap site in the CTL to the Si substrate (or the holes are trapped). Eventually, the stored charge is removed (ie erased). Thus, since the width of hysteresis is used as a memory window for programming and erasing, the CTL must exhibit a large hysteresis in its CV curve, as in a typical CTL Si _x N _y film. In addition, the tunnel oxide must be thin enough to allow tunneling of the charge transporter, and the blocking oxide must be thick to prevent charge injection from the upper electrode during erase.

Recently, for a new application of a charge trap flash memory, nano-dots that replace the Si _x N _y film, graphene and organic - the study of new CTL materials, such as inorganic composite film came bar, in the present invention it is used as a CTL 1: 4 The charge trapping behavior was observed using an alloy film. The memory capacitor used in the present invention is composed of all layers of blocking oxide (Al ₂ O ₃ , 20.5 nm), CTL (1: 4 alloy film, 1.4 nm) and tunnel oxide (Al ₂ O ₃ , 6.5 nm) except the Au electrode. Continuous growth on SiO ₂ (2 nm) / p- Si was achieved without breaking the vacuum of the ALD reactor, which is an important advantage of the memory structure used in the present invention in terms of manufacturing.

FIG. 11B shows the C - V hysteresis characteristics of the memory capacitor normalized to the capacitance with the dielectric capacitance ( C _D = 2.34 × 10 ⁻¹⁰ F) obtained in the accumulation region. The width of the hysteresis of approximately Δ V _FB is 60mV in the middle sweep range (-10 V ~ 10 V, broken line). When reading stored charges, the amount of stored charges should not change by applying a read voltage. Therefore, the capacitor used in the present invention preferably exhibits a small hysteresis in the voltage range of -10 V to 10 V, since the read voltage can be selected in the voltage range. However, as shown in the inset graph of FIG. 11B, the hysteresis width increases as the sweep range increases. Hysteresis width (i.e., Δ V _FB) increases suddenly in a large sweep range of -25 V to 25 V ~ 5.5 V. However, it should be noted that the C - V hysteresis characteristics over a wide sweep range did not shift to a positive value even after voltage stress of +25 V when compared to the CV curve obtained at the narrow sweep. This means that electron trapping in the CTL does not occur due to the absence of electrons that are minority carriers in the p-type Si substrate even by such a high positive bias. Formation of carrier reversal generally requires the presence of a high defect density in the doped n-type source and drain or Si. However, the memory capacitor according to the present invention is not the case, so the charge carriers are holes, and 'programming' corresponds to the release of holes captured during the previous 'erasing' voltage process.

In addition, through this apparent counterclockwise hysteresis, holes are trapped in the CTL under an applied erase voltage (eg -25 V) and holes are emitted from the CTL under an applied programming voltage (eg 25 V). You can see that. The number of charges captured during the sweep of the midrange (-10 V to 10 V) voltage is calculated by Equation 7 as ~ 7.0 × 10 ¹⁰ / cm ² . However, the number of electric charges in a wide range sweep (-25 V ~ 25 V) that contribute to the large width (Δ V _FB ~ 5.5 V) of the hysteresis is ^{~ 6.4 × 10 12 / cm 2} . It can be seen that since the charge must be injected from Si to CTL by tunneling, the amount of trapped charge varies greatly depending on the applied electric field.

The programming / erase behavior by charge trapping in the alloy film is shown in FIG. 12. As a reference state for erasing, the present invention selects a state in which charge is captured by applying -20 V for 1 second. After the memory capacitor was erased to the reference state, programming was performed by applying 20V for each duration. The flat band voltage was obtained from a C - V curve measured in the range of V _FB ± 1 V. Similarly, V _FB for erasure (empty circles) for each duration was measured using another reference state obtained by applying 20 V for 1 second. In Fig. 12, as the duration becomes longer, V _FB moves in the positive direction in programming and in the negative direction in erasing. This shows that the charge density trapped in or exiting the CTL depends on the voltage duration according to equation 6 (where Q is a function of the duration).

Finally, referring to FIG. 13, the present invention examined how long the programmed charge state (solid circle) of the CTL can be maintained. When an erase voltage of -20V was applied for 10 seconds (ie, when holes were captured), the initial V _FB was -1.82V. Subsequently, programming was performed on the memory capacitor by applying 20 V for 10 seconds (ie, when holes were released), and in the present invention, the change of V _FB was observed at room temperature with respect to the elapsed time as shown in FIG. 13. . As the elapsed time becomes longer, V _FB gradually decreases from the initial value of 0.62 V, which is due to the recapture of stored holes. The initial density of holes released from the CTL is calculated to be ~ 2.83 × 10 ¹² / cm ² using an initial value of 2.44 V of V _FB . After 10 years, the estimate of V _FB can be -0.62 V according to extrapolation as indicated by the dashed line in FIG. 13. Using Equation 7, holes recaptured over a decade are expected to be 1.44 × 10 ¹² / cm ² . Thus, half of the charge released is expected to be recaptured for 10 years.

Similarly, retention characteristics of the erased state are also shown in FIG. 13 (hollow circle). During repeated electrical measurements, the memory capacitors used in the retention test were electrically decomposed. Thus, retention of the erased state was investigated on different capacitors in the same specimen. When the programming voltage (20 V) was applied for 10 seconds (ie holes were released), the initial V _FB was -0.78 V. Subsequently, an erase voltage (ie, trapping holes) was applied -20 V for 10 seconds. After elimination, the initial V _FB was -2.20 V and the deduced 10 years later was -1.28 V. Therefore, the initial density of the holes trapped in the CTL was ~ 1.65 × 10 ¹² / cm ² by using the Δ V _FB = 1.42 V. Since Δ V _FB can be 0.5 V after 10 years, the holes retained during CTL will be 5.80 × 10 ¹¹ / cm ² . ~ 65% of trapped holes will be released from CTL for 10 years.

In summary, in the present invention, MLD of the organic-inorganic composite thin film was performed using trimethylaluminum and p -phenylenediamine. This composite film was able to grow through a self-limiting growth mechanism, but showed very low stability in air. Therefore, the composite layer was alloyed with an Al ₂ O ₃ layer to form an alloy film, thereby greatly improving low stability. The resulting alloy film showed excellent insulating properties. For example, the leakage current density of a 1: 4 alloy film was ˜2.3 × 10 ⁻⁸ A / cm ² at an electric field of 1 MV / cm, The dielectric breakdown field was at 2.9 MV / cm. The dielectric constant of the 1: 4 alloy film was ˜6.2.

More interestingly, these alloy films exhibited pronounced charge trapping behavior and exhibited charge trapping properties that could be used as CTLs. Thus, considering the flexibility of alloy film design by structural modification of organic parts, CTL using organic-inorganic alloy films according to the present invention may be a promising candidate for the application of new charge trap memories.

Claims (12)

1) treating trimethylaluminum on the substrate by molecular layer deposition, purging with nitrogen gas, and then treating p-phenylenediamine by molecular layer deposition to form an organic-inorganic hybrid thin film on the substrate; And
2) Treating trimethylaluminum by atomic layer deposition on the substrate on which the organic-inorganic hybrid thin film is formed, purging with nitrogen gas, and treating water by atomic layer deposition, the Al ₂ O ₃ thin film on the substrate Forming steps
Method for producing an organic-inorganic alloy film comprising a. The method of claim 1, wherein the thickness of the organic-inorganic hybrid thin film is 0.1 to 1 nm, and the thickness of the Al ₂ O ₃ thin film is 0.1 to 1 nm. The method of claim 1, wherein after the step 1) is repeated once to five times, the step 2) is repeated once to ten times. The method of claim 1, wherein the relative ratio between the number of repetitions of step 1) and the number of repetitions of step 2) is 1: 1 to 1:10. The method of claim 1, wherein in the molecular layer deposition method of step 1), the dosage of trimethylaluminum is 1 × 10 ⁻⁵ mol / s to 1 × 10 ⁻³ mol / s, and the p-phenylenediamine The dosage is 1 × 10 ^-7 mol / s to 1 × 10 ^-5 mol / s. The method of claim 1, wherein in the atomic layer deposition method of step 2), the dose of trimethylaluminum is 1 × 10 ⁻⁵ mol / s to 1 × 10 ⁻³ mol / s, and the dose of water is 1 ×. ^10-5 mol / s to 1 × 10 ^-3 mol / s method for producing an organic-inorganic alloy film, characterized in that. The method of claim 1, wherein the entire step including the steps 1) and 2) is repeated 1 to 100 times. The method of claim 1, wherein the purging process using nitrogen gas in steps 1) and 2) is performed for 0.1 second to 10 minutes. The method of claim 1, wherein the step 1) is performed in a molecular layer deposition apparatus maintained at a temperature of 100 ° C to 400 ° C and a pressure condition of 100 mTorr to 10 Torr. The method of claim 1, wherein the step 2) is performed in an atomic layer deposition apparatus maintained at a temperature of 100 ° C to 400 ° C and a pressure condition of 100 mTorr to 10 Torr. The method of claim 1, wherein the substrate is a substrate made of Si, glass, plastic, or a metal material. An organic-inorganic alloy film produced by the method according to any one of claims 1 to 11.

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